Serious audio help needed

I just finished installing my front speakers to complete my system, but I'm having some problems. For the record, I have a Pioneer DEH-1400 head unit(20 RMS, 45 MAX), Infinity Referance 3-way 6x9s, and Infinity Referance 4x6 plate speakers(3.5 inch woofer and silk dome tweeter). I also installed bass blockers with the front speakers because of recommendations from both members of some message boards and Crutchfield.
My problem is that I think everything sounded better with the stock front speakers. Everything sounds hollow up front and I'm wondering if it is the bass blockers that is causing this. It almost sounds like I've lost half of the midrange, lower voices are sort of cut out. I have no bass whatsoever up front(due to blockers I'm sure) and it sounds bad. Can I remove the bass blockers without causing damage to the 4x6 speakers?? Do the Infinities have internal crossovers to keep low notes from destroying the tweeter?
When I made the install, I noticed the factory tweeter(in sail panel at top of door) was wired in parallel with the speaker, so I connected it(tweeter) along with the Infinities. Could notes from the factory tweeter be causing any distortion? Would I be better off without it?
Thanks to anyone who responds!
-Marksman

Edited to add: Could it be that the speakers are not getting enough power? Would a 4-way amp help things?

I would wire the tweeters seperately if I were you. Also try taking the bass-blockers out, infinity's should handle the frequencies fine. That hollow sound is exactly what I thought when I had the bass on my HU turned down on accident.

Beleive it or not, some bass blockers can actually INCREASE bass. You may not believe me, but i have charts and proof in books if you need to see for yourself. Adding an amp to anything will always make it sound better. I would say take your bass blockers out. Wire each speaker on a seperate channel into the HU. You should usually never bridge a head unit like it sounds like was done in your case, then play around with the fading and balancing and level controls on the HU and see what you can get.

Try this out and see where that puts you. If you are still lacking, an amp may be in your future....

Depending on the x-over freq. the Infinity speakers could sound weak.
The 4x6 should probably be cut-off around 120Hz.
The 6x9 should be able to handle down to 60Hz.
It depends on if you have a sub to blend in bass.

I would not wire the factory tweeter in with the Infinity speakers.
It will drop the ohm load to the HU down to low. "OVER HEAT"or "BLOW"
It could also add harsh highs into the mix.

The Infinity 4x6 and 6x9 do have a x-over to protect the tweeter.

A 4ch. amp could help if it has built-in x-overs for the front and rear.
But, if your problem is lack of bass up front your best solution is to install some speakers that can produce bass up front. Thus improving your imaging up front.

Basically, I would try different x-over points for the front without exposing them to damaging low freq. material and hear what happens.

Alright thanks for the help! So I assume now that I can remove the bass blockers without damaging the speakers? That is my main concern(why I bought the things in the first place) I'll do that and disconnect the factory tweeter.
I'll try and do it tomorrow and report back with the results.
Thanks and keep the ideas coming!
-Marksman

HOOOOLLLLLLEEEEEEEEEEEEE WWWWWOOOOOWWWW do they sound good!! Tons better than before and way better than the factories! It sounds sooo sweet! No more hollow sound and no more highs that hurt my ears! Everything is clean, crisp, and SWEET!
Thanks to everybody for their help!
If anybody is looking for an awesome sound upgrade pick up Infinity Referance 3-way 6x9s and 4x6 plates! Do not buy bass blockers
Thanks again!
-Marksman